The present invention relates to a method of and apparatus for continuously soldering small elements arranged generally in a line by a concentrated radiant energy source.
Soldering by hand has long been known. However, when the elements to be soldered are small, difficulties arise in that with hand soldering it takes a very long time to complete a small element such as a circuit board having many conductors to be soldered, and that bridging or insufficient solder strength can not completely be avoided even when careful work is performed.
Another known method to solder small elements utilizes electric resistance heating or ultrasonic energy. However, melting of wires or insufficient solder strength also tends to occur with this method, and a long time is required to connect a great many conductors.
It is also known to use an infrared radiant lamp to melt solder. Usually, the lamp concentrates a radiant beam in the form of an elongated band or line from the elongated lamp. Concentrated radiant heating itself is useful and advantageous. There is complete absense of physical contact, thus heater born contamination and disturbing forces on the elements to be soldered are eliminated. Also, it applies heating energy rapidly without disturbing surrounding structures. Soldering by means of an elongated lamp furthermore can treat a great many elements arranged in a line by only one process. However, temperature distribution along the line tends to differ and insufficient heating and overheated portions tend to occur. Also, the lamp and the control device must be very precise to attain the desired result.
Concentrated spot radiation beam heating by moving the source along a line of elements to be soldered is also utilized. However, by continuously moving the beam, temperature distribution is not satisfactory along the line of elements to be soldered, and the line tends to overheat as the lamp is moved. Thus satisfactory results are not easily attained.